一种新的乙型肝炎病毒表面抗原结合蛋白的筛选、表达及其生物学活性的初步研究

为了研究乙肝病毒侵染肝细胞过程中的功能蛋白 ,通过印迹免疫分析技术从人肝cDNA噬菌体表达库中筛选出一株编码乙肝表面抗原结合蛋白 (hepatitisBsurfaceantigenbindingprotein ,HBsAg BP)的cDNA克隆 .基因测序结果表明 ,该cDNA具有独立的开放阅读框架 ,编码 1个由 344个氨基酸残基构成的可溶性蛋白分子 ,属于免疫球蛋白超家族成员 .将该基因克隆到原核表达载体pTriplEx后 ,在E .coliXL1 Blue菌株中获得 4 4kD的重组蛋白 .重组蛋白经Western印迹和ELISA实验证明具有与乙肝表面抗原特异性结合的能力 .进一步经流式细胞仪实验显示 ,在纯化的重组蛋白存在的情况下 ,天然的HBsAg与肝细胞株HepG2的亲和力显著增高 .结果显示 ,该乙肝表面抗原结合蛋白可能是介导乙肝病毒对肝细胞亲和侵染的可溶性辅助受体 .     

小环载体介导的siRNA 稳定抑制乙肝病毒的复制和表达

【目的】尝试构建表达小干扰RNA(small interfering RNA,siRNA)的小环载体,并初步鉴定其对乙肝病毒(hepatitis B virus,HBV)复制及其基因表达的抑制作用。【方法】设计并合成靶向HBV S区的siRNA,将其克隆到小环载体pMC.BESPX-MCS2上,测序正确后将重组体pMC-H1-siHBS-U6转化入感受态E.coliZYCY10P3S2T,然后在培养基中加入L-阿拉伯糖,诱导其降解细菌骨架,获取只含有目的基因表达盒的小环RNA干扰载体pmc-H1-siHBS-U6。将小环RNA干扰载体与HBV真核表达质粒pHBV1.3共转染Huh-7细胞,分别在转染后1-7天,ELISA法检测Huh-7细胞上清中的HBsAg、HBeAg,并且通过Real-time RT-PCR法分析干扰RNA对HBV DNA及mRNA的抑制效果。【结果】成功构建了靶向HBV S基因的siRNA小环表达载体pmc-H1-siHBS-U6。该载体能显著抑制Huh-7细胞HBsAg和HBeAg分泌,并且其抑制效果能够维持2-3周时间。Real-time PCR证实HBV的DNA与mRNA水平分别降低了71%和80%,而对照siRNA及空载体则无此作用。【结论】成功构建了靶向HBV的小环RNA干扰载体,并且其能稳定、高效、特异地抑制HBV基因的表达与复制,该研究不仅对探索HBV的基因治疗提供了重要线索,而且为RNA干扰的应用提供了新的运载体系。     

杜氏盐藻外源基因稳定表达系统的构建(英文)

A stable transformation system for the expression of foreign genes in the unicellular greenmarine alga (Dunaliella salina Teod.) was established. Using electroporation, the alga was transformed witha plasmid containing the hepatitis B surface antigen (HBsAg） gene and the chloramphenicol acetyltransferase(CAT) gene as a selectable gene. PCR and Southern blotting analysis indicated that the HBsAEgene wasintegrated into the D. salina genome. Northern dotting analysis showed that the HBsAg gene was expressedat the mRNA level. The stable expression of HBsAg protein in transformants was confirmed by HBsAgenzyme-linked immunosorbent assay (HBsAg EUSA) and Western blotting analysis. Also, PCR and Southernblotting analyses showed that the CA Tgene was integrated into the D, salina genome, and CAT EUSAindicated that CAT protein was stably expressed in the cells. The introduced HBsAg DNA and HBsAgprotein expression were stably maintained for at least 60 generations in media devoid of chloramphenicol.This is the first report of the stable expression of foreign genes in D. salina.     

杜氏盐藻外源基因稳定表达系统的构建

建立了一种单细胞海水绿藻--杜氏盐藻(Dunaliella salina Teod.)的外源基因稳定表达系统.通过电激法将携带乙肝病毒表面抗原基因(HBsAg)和氯霉素乙酰转移酶基因(CAT)的质粒转入盐藻细胞内,CAT基因为筛选基因.PCR和Southern杂交结果显示,HBsAg基因已经整合到盐藻基因组中.Northern杂交结果表明,转化成功细胞内的该基因已转录成mRNA.HBsAgELISA和Western杂交检测证明,HBsAg蛋白在转化的盐藻细胞内稳定地表达.同时,PCR和Southern杂交显示,CAT基因也已整合到盐藻基因组中.且CATELISA检测证明,CAT蛋白在转化体中也已稳定地表达.进一步对转化盐藻进行无氯霉素筛选培养,60代后,HBsAg基因依然稳定地存在并表达.本实验第一次报道了外源基因在杜氏盐藻细胞内的稳定表达.     

肝细胞靶向性系统表达载体的构建

在肝脏疾病的基因治疗过程中,为把目的基因定向导入靶细胞,构建了具有靶向性的逆转录病毒的包装细胞．即应用RT-PCR方法分别反转录并扩增env,pres2基因,将它们分别克隆至pGEM-T载体上,经测序正确后,将一目的基因亚克隆在pcDNA3．1(-)表达载体上,然后将另一目的片段从T载体上切下,克隆至经同样酶切的重组表达载体中。从而成功地构建了肝细胞靶向性系统的表达载体pcDNA3．1(-)-env-pres2和pcDNA3．1(-)-pres2-env。     

Insulin Dominantly Suppresses Hepatitis B Virus Gene Expression in Cultured Human Hepatoma Cells

We have shown previously that insulin suppresses the expression of hepatitis B surface antigen (HBsAg) gene from an endogenous integrated viral genome in cultured human hepatoma Hep3B cells. In this study, we demonstrated that insulin suppresses the viral mRNA transcribed from transiently transfected tandem repeat hepatitis B virus (HBV) dimer DNA or DNA fragment that contains only the major HBsAg gene. Insulin treatment also resulted in a decrease in HBV viral particles produced by the HBV-DNA-transfected cells in a dose-dependent manner. Furthermore, when insulin was simultaneously added with glucocorticoid, which stimulates HBV gene expression, the stimulatory effect of glucocorticoid was completely abolished. Our results suggest that insulin has a dominant negative effect on the HBV gene expression in cultured human liver cells.     

含庚型肝炎病毒E2基因片段质粒DNA能诱发相当强烈的体液免疫应答

研究了庚型肝炎病毒E2(HGV E2)基因片段作为DNA疫苗的可行性。将来自于质粒pThioHis-E2编码HGV E2的基因片段(559bp)亚克隆到质粒pCMV-S中,使之和HBsAg基因位于同一阅读框,形成重组质粒pCMV-S-E2。用纯化的质粒pCMV-S-E2 DNA注射到昆明小鼠后腿四头肌中来免疫小鼠,同时用pCMV-S作为对照。间隔14天再加强一次免疫。在加强免疫后的第8天眼眶取血。用E2—GST融合蛋白作为固定化抗原,通过ELISA检测受试小鼠的体液免疫应答。结果表明,用质粒pCMV-S-EDNA免疫的小鼠可以产生很强的体液免疫应答。     

表达乙型肝炎病毒表面抗原基因又形成多角体的杆状病毒

用形成包含体(OCC~+)并能利用人工合成启动序列和多角体XIV启动子表达外源基因的转移载体质粒pSXIVVI~+X3,将乙型肝炎病毒表面抗原(HBsAg)基因和多角体基因同时插入无包含体的粉纹夜蛾核型多角体病毒TnNPV-SVI-G基因组中,得到表达HBsAg基因又形成包含体(多角体)的重组毒侏TnNPV-HBs85-OCC~+。与利用野生型多角体启动子表达HBsAg基因的无包含体毒株TnNPV-HBsD4不同,TnNPV-HBs85-OCC~+由于具包含体,能以口服方式大规模感染粉纹夜蛾(Trichoplusia ni)幼虫,且HBsAg基因在草地夜蛾(Spodoptera frugiperda)离体细胞中的表达量要比前者高约37％,在虫体中的表达则更高。     

IL-12增强HBV融合抗原DNA疫苗在小鼠诱导的细胞免疫应答

乙型肝炎病毒(hepatitis B virus,HBV)极易形成慢性感染,主要机制在于感染者不能产生强有力的细胞免疫应答以清除病毒[1].慢性HBV感染者体内虽然存在HBV抗原特异性T淋巴细胞,但对HBV抗原的反应性较低.研究发现,增强这类T淋巴细胞的反应性,可以促进HBV的清除[2].     

Expression of foreign antigens on the surface ofEscherichia coli by fusion to the outer membrane protein TraT

ThetraT gene is one of the F factor transfer genes and encodes an outer membrane protein which is involved in interactions between anEscherichia coli and its surroundings. This protein was altered so as to permit the expression of foreign proteins on the outer membrane ofE. coli in this study. A 729-bp DNA fragment, including the leader and entire structural gene sequence oftraT, was amplified and obtained by PCR. This sequence was then subcloned downstream of thetac promoter of pDR540, resulting in a TraT expression vector, pT2. Here, we report that the expression of TraT protein, fused either with a partial pre-S antigen of hepatitis B virus (60 and 98 amino acids, respectively) or with the snake venom rhodostomin (72 amino acids), was successfully achieved on the outer membrane ofE. coli, using the pT2 plasmid. This result was demonstrated using dot blot and immunofluorescence analysis. This finding supports the notion that the pT2 plasmid can be used as anE. coli display system. This system can detect a foreign peptide of about 100 amino acid residues in length on the bacterial surface.     

Baculovirus as a highly efficient gene delivery vector for the expression of hepatitis delta virus antigens in mammalian cells

Baculovirus has been employed for a wide variety of applications. In this study, we further expanded the application to the high-level expression of hepatitis delta virus (HDV) antigens and the formation of virus-like particles (VLP) in transduced mammalian cells. To this end, two recombinant baculoviruses were constructed to express large hepatitis delta antigen (L-HDAg) and hepatitis B surface antigen (HBsAg) under mammalian promoters. With a simplified transduction protocol using unconcentrated virus, high transduction efficiencies were achieved in hepatoma cells, in which L-HDAg and HBsAg were expressed abundantly, allowing for easy colorimetric detection in Western blots. L-HDAg alone was nucleus-bound and HBsAg alone was secreted; formation and secretion of HDV-like particles were readily detected upon coexpression, indicating that the baculovirus-expressed proteins were processed correctly as the authentic proteins. Quantitative real-time PCR (Q-PCR) analyses quantitatively revealed that baculovirus transduction was more efficient than plasmid transfection with respect to DNA uptake and DNA transport to the nucleus. Furthermore, superinfection introduced more baculovirus DNA into cells in the long-term culture as revealed by Q-PCR, thereby enhancing and prolonging the expression. In summary, baculovirus transduction can be an attractive method as an alternative to the plasmid transfection commonly employed for HDV research thanks to the significantly higher gene delivery efficiencies as well as the abundant expression and proper processing. Baculovirus can also be envisaged as a useful tool for investigating protein-cell interactions and virus assembly.     

Expression and Characterization of Hepatitis B Surface Antigen in Transgenic Potato Plants

Transgenic potato plants expressing the gene of hepatitis B surface antigen (HBsAg) under the control of the double promoter of 35S RNA of cauliflower mosaic virus (CaMV 35SS) and the promoter of patatin gene of potato tubers have been obtained. Biochemical analysis of the plants was performed. The amount of HBsAg in leaves, microtubers, and tubers of transgenic potatoes growing in vitro and in vivo was 0.005-0.035% of the total soluble protein. HBsAg content reached 1 microg/g in potato tubers and was maximal in plants expressing the HBsAg gene under the control of CaMV 35SS promoter. In transgenic plants expressing HBsAg gene under the control of tuber-specific patatin promoter, HBsAg was found only in microtubers and tubers and was absent in leaves. Western blot analysis of HBsAg eluted from immunoaffinity protein A-Sepharose matrix has been performed. The molecular weight of HBsAg peptide was approximately 24 kD, which is in agreement with the size of the major protein of the envelope of hepatitis B virus. Using gel filtration, it was determined that the product of HBsAg gene expression in potato plants is converted into high-molecular-weight multimeric particles. Therefore, as well as in recombinant HBsAg-yeast cells, assembling of HBsAg monomers into immunogenic aggregates takes place in HBsAg-transgenic potato, which can be used as a source of recombinant vaccine against hepatitis B virus.     

Expression and characterization of hepatitis C virus core protein fused to hepatitis B virus core antigen

Recombinant plasmids were constructed by fusing the gene fragments encoding the full-length (1-191aa) and the truncated (1-40aa and 1-69aa) HCV core proteins (HCc) respectively to the core gene of HBV at the position of amino acid 144 and expressed in E. coli. The products were analyzed by ELISA, Western blotting as well as the immunization of the mice. The results showed that those fusion proteins (B144C191, B144C69, B144C40) possessed the dual antigenicity and immunogenicity of both hepatitis B virus core antigen (HBcAg) and hepatitis C virus core protein (HCc). Analysis by electron microscopy and CsCl density gradient ultra-centrifugation revealed that similar to the HBcAg itself, all fusion proteins were able to form particles. Comparison of the antigenicity and immunogenicity of those fusion proteins showed that the length of HCc gene fused to HBeAg had no much effect on the antigenicity and immunogenicity of HBcAg, however, B144C69 and B144C40 induced higher titres antibodies against HCc than B14d     

Identification of vaccinia promoters by heterologous expression of hepatitis B surface antigen in mouse cells infected by recombinant vaccinia viruses

DNA fragments preceding open reading frames in a conserved segment of the vaccinia virus genome (Plucienniczak A., et al. (1985) Nucleic Acids Res. 13, 985–998) were cloned into plasmids upstream of the S gene of the hepatitis B virus encoding the surface antigen (HBsAg). Recombinant vaccinia virus obtained after insertion of these constructs into the thymidine kinase gene were used to infect mouse 1D cells. HBsAg was assayed in cellular supernatants. A strong promoter was thus identified in a 295 bp fragment preceding the coding region of the 147 kDa subunit of the vaccinia RNA polymerase.     

乙肝病毒表面抗原持续表达的新致病机制

乙型肝炎表面抗原(HBsAg)持续阳性是控制乙肝中难以解决的重大问题。本研究通过揭示HBsAg致病机制的基础研究,寻找抑制或清除HBsAg的新途径。通过建立有可比性的HBsAg转基因鼠和稳定表达细胞系及相应对照,进行比较转录组学和蛋白质组学研究,发现了HBsAg在HBV慢性感染中的一些新致病机制。其中包括:HBsAg促进肝细胞内CypA分泌,后者可趋化炎症细胞在HBsAg阳性灶周围浸润;在细胞模型中,HBsAg分泌可引起胞内GRP78蛋白下降,导致肝细胞抗凋亡能力减弱;发现HBsAg在细胞中可上调截短的LEF1基因的表达,缺乏活化全长LEF1促成瘤和增殖活性;而肝癌组织中LEF1则倾向于核内分布,并活化Wnt下游基因Cyclin D1与c-myc,有促肿瘤活性。在转基因鼠和细胞模型中都发现了物质和能量代谢相关的基因发生变化,并与临床慢性乙肝患者表现相符。研究中有关CypA的发现提供了抑制HBsAg的新途径;有关代谢的变化提出了改变饮食内容与习惯可能有利于HBsAg阳性感染者的预后。     

生物可降解微球作为乙型肝炎基因免疫佐剂的研究

探讨生物可降解微球对基因免疫的增强作用。采用有机溶剂蒸发法制备聚乳酸聚乙醇酸共聚 物（ＰＬＧＡ）微球,构建含有乙型肝炎病毒表面抗原Ｓ基因的ｐＲＣ－ＣＭＶ真核表达载体,用微球与基因 载体共孵育法制备其混合物。肌肉注射免疫Ｂａｌｂ／ｃ小鼠。结果表明：微球注射组的血清抗体滴度达到 ｌ：１６００,其效果与乙型肝炎病毒表面抗原加铝佐剂注射组相近,而裸ＤＮＡ注射组没有反应。说明了 生物可降解微球可显著的提高基因免疫的免疫反应。     

乙肝病毒DNA疫苗的构建及其诱导小鼠的免疫应答

构建含adr亚型HBV表面抗原基因的核酸疫苗 ,考察人白细胞介素II基因及重组白细胞介素II的免疫佐剂作用。用含有人白细胞介素II基因的真核表达质粒及基因重组白细胞介素II蛋白作为佐剂 ,将编码乙型肝炎病毒表面抗原的重组真核表达质粒 pVAX/HBS免疫BALB/C小鼠 (试验组 ) ,同时设置注射质粒pVAX的阴性对照组 ,并分别于第 2 ,4周后加强免疫各 1次。试验组在第 4周时开始有HBsAb产生 ,阴性对照组未测到HbsAb ,试验组和对照组均未检测到HBsAg。乙肝病毒DNA疫苗能引起小鼠特异性体液免疫应答 ,白细胞介素II的真核表达质粒的佐剂作用不明显 ,基因重组白细胞介素II蛋白具有提高小鼠对乙肝病毒核酸疫苗免疫应答水平的佐剂活性。     

麻疹病毒血凝素基因工程抗原及其抗原性检测(英文)

将麻疹病毒 (Nepal株 )的血凝素 (hemagglutinin)基因插入真核表达载体pIRES EGFP ,并在HeLa细胞中表达 .因其较低的表达量 ,所以将其截短 ,去除跨膜区 .使这个截短的HA基因与绿色荧光蛋白基因融合 ,并克隆至原核表达载体pET 2 8b中 .将重组质粒转入大肠杆菌中表达 ,产生了分子量约为 90kD的融合蛋白 .通过ELISA和Western印迹来检测这个基因工程蛋白的抗原性 .在检测一系列的血凝素阳性或阴性的人血清中 ,这个融合蛋白的阳性检出率为 90 % ,阴性检出率为 10 0 % (与市售麻疹病毒诊断试剂盒相比较 ) .由于此HA蛋白是原核表达产物 ,回避了真核表达系统复杂的操作过程和昂贵的费用 ,所以 ,这个麻疹病毒血凝素基因工程抗原有望成为一种新型、便捷的麻疹病毒诊断试剂     

乙型肝炎病毒表面抗原对细胞脂质合成作用的研究

乙型肝炎病毒(hepatitis B virus,HBV)合成的蛋白调节细胞脂质代谢的研究不断被报道,但乙型肝炎病毒表面抗原(hepatitis B virus surface antigen,HBsAg)与脂质代谢的相互调控研究较少,且机制尚不明确。本研究通过对细胞转录组学的分析,揭示HBsAg对脂质代谢的调控机制。选用稳定表达HBsAg的细胞系HepG2-S-G2与其对照细胞系HepG2-neo-F4进行转录组学分析。利用定量聚合酶链反应(polymerase chain reaction,PCR)、蛋白质印迹法(Western blot,WB)分别检测重要差异基因OXCT1和CYP4F3在mRNA水平和蛋白水平的表达差异。为验证HBsAg促进脂质合成上调的表型,对两种细胞系进行油红O染色并检测细胞脂肪酸、总胆固醇水平。进一步对稳定转染HBV的细胞系HepG2.2.15进行降脂处理,以观察细胞上清液中HBsAg与脂质合成之间是否存在相互调控。结果显示,参与脂质代谢的差异基因发生显著变化,提示HBsAg引起了宿主细胞脂质合成途径的上调和消耗途径下调。定量PCR结果显示,相对于HepG2-neo-F4细胞,HepG2-S-G2细胞的3-酮酸辅酶A转移酶1(3-oxoacid CoA-transferase 1,OXCT1)mRNA水平升高约9倍,与转录组测序结果基本一致;CYP4F3基因在HepG2-S-G2细胞中转录相对下调。 WB结果显示,OXCT1和CYP4F3蛋白表达均出现相应的显著上调或下调,并且趋势与转录组分析一致。油红O染色以及细胞脂肪酸、总胆固醇水平检测结果证实HepG2-S-G2细胞中脂滴更明显,且游离脂肪酸和总胆固醇均显著升高。降脂处理结果显示细胞上清液中HBsAg显著降低。上述结果表明,HBsAg可上调脂质代谢、促进脂质合成,提示降脂可能成为抑制HBsAg的潜在有效途径。